Patients with infective endocarditis (IE) have a poor prognosis with one third of the patients succumbing to the infection within the first year. Treatments for endocarditis involve antibiotic therapy and/or surgery that cost upwards of $100,000 per patient; however, many cases do not respond to the antibiotic treatment and surgery poses high risks. Cases of endocarditis that are recalcitrant to antibiotic therapies are often caused by drug- resistant organisms, in particular methicillin-resistant Staphylococcus aureus (MRSA). Agile Sciences is developing an alternative approach to treating resistant bacterial infections that bypasses many of the inherent limitations of developing new antibiotics. Agile Sciences' technology does not act as a microbicide to the bacteria, but instead inhibits antibiotic defense mechanisms, so that resistant strains become susceptible to traditional antibiotic therapies. Agile Sciences' co-founders, Drs. Christian Melander and John Cavanagh of North Carolina State University, have developed a new class of 2-aminoimidazole (2-AI) small molecules that bind to a novel protein target within the bacteria. These 2-AI molecules inhibit the ability of the bacteria to respond to environmental stimuli, including antibiotics, thu rendering the bacteria more sensitive to antibiotics. Agile Sciences' 2-AI compounds have been shown to lower the MIC of cell wall-acting antibiotics against MRSA, and this novel class of 2-AI compounds also inhibits and disperses MRSA biofilms. Preliminary studies indicate that these 2-AI compounds have favorable toxicity and metabolic stability profiles, and so they represent promising scaffolds for evaluation as potential therapeutics. The overarching goal of this proposal is to obtain proof of concept that Agile Sciences' 2-AI compounds enhance antibiotic efficacy against MRSA in an in vivo model of IE. The objective of Aim 1 is to rank lead compounds using assessments of biological activity, toxicity, and pharmacokinetic properties. In Aim 2, the most promising 2-AI compound will be evaluated for in vivo effectiveness as an antibiotic adjuvant therapy in a well-established rat model of IE. This project will be overseen by Dr. Angela Pollard, a microbiologist with expertise in microbial colonization and host-pathogen interactions. The in vivo model will be executed by an experienced team of UCLA scientists led by Dr. Yan Xiong, with consulting expertise by Dr. Arnold Bayer, a well-known expert in endocarditis models. Physician Dr. Ralph Corey of Duke University will contribute valuable clinical insight to this project. If Agile Sciences' 2-AI compounds are successfully shown to enhance the activity of current antibiotics against MRSA in an in vivo model of IE, this new class of molecules could potentially provide a more effective therapeutic strategy for treating IE infections that are currently resistant to treatment. As a result of this improved therapy, the high costs and risks of surgery as well as the substantial mortality rate associated with this disease could potentially be significantly reduced.